When the pilot pushes his PTT, there is carrier but no modulation. What is the most common cause of this?
(Please note this answer only applies to stand alone Intercoms.) The most common cause of this problem is that the installer failed to provide independent PTT wires to the Pilot and Copilot mic jacks. (Additionally, it is highly probable they also failed to install the required AUX Mic and AUX Headphone jacks, see FAQ #23). There is a voting system in the intercoms, and if the pilot’s PTT is not hooked up to the Pilot’s Mic jack, and if the copilot’s PTT is not hooked up to the Copilot’s Mic jack, the appropriate mic audio will not get through to the aircraft radio..
